System for producing oscillations



June 9,. 1925.

A. w. HULL SYSTEM FOR PRODUCING OSCILLATIONS Filed May 18, 1

Figl.

Gr id otential nwr; Albert H n by a His orney.

?atented dune 9,

uurrsn' 4 lsnsse ALBERT w. HULL, oi" sonnn'ncrnny, NEW-YORK,

nssrsndn '10 GE ERAL nnncrmc con ress, is CORPORATION on NEW YORK.

sr srnn roe Piiommmo OSCILLATIONS Application filed May 18,,1921. Serial No. 470,723.

To allwlmm it may concern: v

Be it known that l, ALBERT WXH LL a citizen of the United States, residing at Schenectady, in the county or fichenectady,

State of New York, i ventedcertain,

new and useful lnaproveinein-s Systems tor Producing Oscillations, intwhich the :iollowin is a s' ecificaticn. D

My present inventionrelstes to e system -Eor producing OSClllflilHg currents lIlWhlQll 1 an electron discharge device hcvin ge negative resistance characteristic is employed.

In my prior U. S. Patent, No. 1,313,188,

of August 12, 1519, I hs've described a'isystein for producing alternating currents-1n which the generation of oscillations is car- .ricdjout by means of an electron discharge device which is sh ila-ranged as tohave a.

negative resistance characteristic. This de-.

vice consists essentially of electron c it-' ting cathode cnd'two other electrodes enclosed in an evacuated receptecleI The system is so arranged that second cry electrons are emitted from one or the other electrodes,

to such an extent that the resistance between the cathode and the electrode from which system described in my ceived is 'inaintuined ill, constant positive potential. l: have now discovered that t 15 not essentiulutliat the potentici of the electrod-e which receives the secondary elec trons be maintained constant. As aresult I have found that it is possihlcto supply oscillations from the circuit between the cathode and the electrode which receives secondary electrons to a work circuit, and thereby greatly increase the elliciency "of operation of the system. The operntion of this system under these conditions is some- '1 what similar to that ot it threeelectrode or pliotron amplifier in which the grids ex-i cited by means of an oscillating current etnd it greatly amplified alternating current is supplied from the plate circuit, ldyjprescut system, however, diliers in ts operation ii om that of an ordinary nniplii'ler, in that the grid excitation is provided by the openation of the device itself and no separate I source of energy is required for exciting the grid. In so far as the operation of the'device with respect to the production of oscil- ,lations is concerned, my system dilfers from r that of the usual three-electrode oscillators previously employed in that oscillations are produced in one of the circuits independently of any coupling between the circuits between the cathode and the other two elec trodes.

The novel features which I believe-to be .fch'aiscteristic of my invention are set forth with particularly in the appended claims.

My invention itself,-ho wever, both as to its orfganization and method of ope'ration will best understoocl'by reference to the following description taken in connection with 'the,ac-

j cornpanying drawing in which Fig. 1 shows 3'diugrammatical1y a simplecircuit connection wherebymyinvention may be carried intojfeffect, and Fig.2 isa characteristic curve showing the relation between the potentialof the electrode which emits secondary electrons and'the current flowing in the circuit of said electrode.

As indicated in the drawing, I provide an electron discharge device 1 having an. electron emittingcathode 2, an anode 3 and a grid electrode 4 interposed between oath ode and anode. A circuit between the oath ode and grid electrode includesthe induc-' tance 5 and capacity 6 by means of which this circuit'may be tuned to the frequency of the oscillations which it is desired'to pro duce. The circuit between cathode and an ode includes us'ou'rcc'of potential such as a battery 7 and a, primary winding 8 of s, transformer, the secondary 9 of which is included in the, work cir'cuit which in the case illustrated is Imadeup by the antenna, 10 of a radio transmitting system; i I

The connection from the grid, tothe' oath ode may be made by means of the variable connection "11 toa point in the battery 7 whichis so chosen that a positive potential will be impressed upon the grid 4 of the right value to causefoscillations to be prc ducedin the circuit between cathode and grid by reasom of the negative resistance of that circuit as indicated in the curve oi Fig. 2. \Vhen oscillations are produced in the grid circuit the. potential'of the grid. will become alternately positive and negs-' tive with n-espect to the cathode, and the 'ili :of the fact that the plate circuit includes a load the potential of the anode'3 will vary in accordance, with the drop of potential through the load. The only essential for continuous'operation oi the system is that" the potential of-thesource shall be high enough so that the potential of the anode 3" Willialways be enough higher than that of:

the grid 4 to carry off the secondary electrons emitted fronrihe grid at.

v In the system shown in my prior patent referred to above, the ciiiciency of operation depends upon the proper adjustment of the relations between the constants of the oscillating circuit and the load circuit associated therewith. In the present case since the oscillating circuit has fto supply only the current necessary for varying the grid potential and. is not coupled to the other circuit, the'adjustment of this circuit is entirely independent of the adjustment of the. load circuit, and since the energy in the oscillating circuit is but a small part of the total energy of the system the efficiency of operation-of the. oscillating circuit may be comparatively low' without materially afiecting the total efficiency of the system.

i The frequency of the oscillations produced is fixed entirelygloy the tuning of the resonant grid circuit and is essentially in- :dependent of the tuning of the plate and load circuits. In this respect my improved system. offers material advantages over the previously employed three-electrode oscillators in which the grid and plate circuits are coupled together and the plate circuit' is in turn coupled to the load circuit, the frequency of the oscillations in this case being dependent to a large extent upon the tunin of the load circuit.

lVlnle I have shown and described the preferred embodiment of my invention, it will be apparent that my invention is by no means limited to the particular circuit con- "lQCillOllS and apparatus shown, but that nany modifications therein may be made without departing from the scope of my invention. as set 'iorth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1, The combination in a system for producing oscillating currents of an electron discharge device having a cathode, an anode and a grid, grid and plate circuits associated therewith, means for producing an emission of secondary electrons from said grid sufficient to produce a negative resistance characteristic in the grid circuit over a range of positive grid potential and thereby causing the generation of oscillaany coupling between the circuits and a work circuit associated with said plate circuit.

2. The combination in a system or producing oscillating currents of an electron discharge device having a cathode, an anode and a grid, grid and plate circuits asso ciated"therewith, means for producing a g ance characteristic in said grid circuit over a range of positive grid potential by reason of the emission of secondary electrons from saidlgrid and thereby causing the generation of oscillations in said :grid circuit independently of any coupling between the circuits and a work circuit associated with said plate circuit.

3. The combination in a. system for producing oscillating currents of an electron discharge device having a cathode, an anode and a grid, a resonant circuitconnected between said cathode and grid which is tuned to the frequency of the currents to be produced, a. plate circuit connected between said cathode and anode, means for producing a negative resistancg characteristic in said grid circuit over a range of positive grid potential by reason of the iemissio'n of secondary electrons from said grid and a work circuit associated with said plate circuit. 7 4c. The combination in a system for producing oscillating currents of an electron discharge device having a cathode and an anode, and a grid interposed between said cathode and anode a'resonant rid circuit connected between said cathode and grid which includes an inductance and a capacity, a plate circuit connected between said cathode and anode, source of potential in said plate circuit and a work circuit coupled to said plate circuit, the device being so constructed and the potential in said plate circuit being so chosen that a negative resistance characteristic will be produced in saidgrid circuit over a range of positive grid potential by reason of the emission of secondary electrons from said grid whereby oscillations will be produced independently of any coupling between the circuits.

5. The method oii'operating a generating system comprising an electron discharge device having an electron emitting cathode, an anode and a grid and plate and grid circuits associated therewith which consists *tions in said. grid circuit independently of system comprising an electron discharge de vice having an electron emitting cathode, two othe, elect ofdjs, and separate circuits con cted bet "Ween "he cathode and each of gthe'othei electrodes tvhich bonsists in producing oscillating currents of an. electron discharge device having a cathode and two other electrodes, eparate circuits connecting the cathode With each of the other elec trodes, means for producing an emissionof secondary electrons from one of the said electrodes suflicient to produce a negative resistance characteristic in the circuit connected thereto over a range or" positive potential of said electrode,and thereby causing the generation of oscillations in the circuit connected to said electrode independently of any coupling between thecircuits and a work circuit coupled to the circuit which'is connected to the other electrode.

8. The combination in a'system for producing oscillating currents of an electron discharge device having a cathode and two other electrodes, separate circuits connecting the cathode with each of the other" electrodes, means for producing a negative resistance characteristic in one of said circuits over a range of positive potential of the elec-' trode connected thereto by reason of the emission of secondary electrons from the electrode to which the circuit is connected and thereby causing the generation of oscil-, lations in said circuit independently of any coupling between the circuits and a Work circuit coupled to the other circuit. v 9. The combination in a system for producing oscillating currents of an electron discharge device having a cathode and twoelectrodes, separate circuits connecting the cathode to each of the other electrodes, one of said circuits being resonant to the ire quency of the currents to be produced, means for producing a negative resistance characteristic in said resonant/circuit over a range of positive potentiahof the electrode connected thereto by reason of the emission of secondary electrons .from the electrode to which said circuit is connected, and a Work circuit coupled to the circuit of the other electrode. r

in Witness whereof, I have hereuntoset my hand this 17th day of May, 1921." 1 ALBERT WKHULL. 

